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November 29, 2010

Some Reefs Less Vulnerable To Warmer Sea Temps

by Sam Savage

New research highlighting coastal locations where coral can better withstand rising sea temperatures, a leading cause of stress to coral reefs, may guide efforts to conserve the largest living structures on Earth.

The findings hold promise for an estimated 100 million people living along the coasts of tropical developing countries whose livelihoods and welfare depend directly on coral reefs, but are currently under threat from climate change.

In a report published in an online edition of Ecology Letters on November 25, scientists from Australia, the UK, Mexico and the US, mapped coral stress across the Bahamas in the Caribbean and found that sea temperatures, which strongly influence coral health, caused less stress to reefs in certain areas.

This discovery was borne out in the second half of the study, during which the researchers designed marine reserves best-suited to four possible scenarios of how coral would respond to further sea temperature rises. In each hypothetical scenario, 15 percent of the locations in the Bahamas were consistently selected.

While the study's lead author, Professor Peter J. Mumby, from the Global Change Institute and the ARC Centre of Excellence for Coral Reef Studies says the research complicates current understanding of marine reserve design, the findings can help make the best use of the limited resources available for coral reef conservation.

"Designing marine reserves for the long-term is more difficult than we thought", Prof. Mumby says. "The responses of coral to the impacts of climate change are relatively unknown at this stage. Yet the good news is that some geographic locations were consistently selected in the generated scenarios, regardless of how corals might adapt to warmer temperatures.

"These areas are great contenders for early conservation no matter what the future holds". Prof Mumby adds that, "The research found good locations for protecting corals and we are providing this information to conservation partners in the Bahamas to help them in their efforts to work with local communities and establish new reserves."

Prof. Mumby says the response of coral to climate change is an ongoing focus for scientists and conservation advice will be updated regularly to reflect new research findings.

Prof. Mumby says the world's oceans are becoming warmer due to the increasing concentration of atmospheric carbon dioxide produced by the burning of fossil fuels. A rise in sea temperature by as little as 1°C causes stress to corals and can lead to coral bleaching, where corals lose their internal symbiotic algae that help them grow, and may result in vast areas of dead coral.

Scientists expect that warming sea temperatures could cause coral to die in large numbers. The destruction of coral reef ecosystems will expose people in coastal areas of developing countries to flooding, coastal erosion and the loss of food and income from reef-based fisheries and tourism.

The project was funded by the Coral Reef Targeted Research & Capacity Building for Management (CRTR) Program, Khaled bin Sultan Living Oceans Foundation, National Environment Research Council, European Space Agency and the EU Seventh Framework Program.